Surface-textured encapsulations for use with light emitting diodes

ABSTRACT

Surface-textured encapsulations for use with light emitting diodes. In an aspect, a light emitting diode apparatus is provided that includes a light emitting diode, and an encapsulation formed upon the light emitting diode and having a surface texture configured to extract light. In an aspect, a method includes encapsulating a light emitting diode with an encapsulation having a surface texture configured to extract light. In an aspect, a light emitting diode lamp is provided that includes a package, at least one light emitting diode disposed within the package, and an encapsulation formed upon the at least one light emitting diode having a surface texture configured to extract light. In another aspect, a method includes determining one or more regions of an encapsulation, the encapsulation configured to cover a light emitting diode, and surface-texturing each region of the encapsulation with one or more geometric features that are configured to extract light.

RELATED APPLICATIONS

This patent application is a Divisional patent application of patentapplication Ser. No. 12/163,594, filed on Jun. 27, 2008 entitledSURFACE-TEXTURED ENCAPSULATIONS FOR USE WITH LIGHT EMITTING DIODES, theentire content of which is hereby expressly incorporated by reference.This patent application is also related to patent application Ser. No.12/704,326, filed on Feb. 11, 2010 entitled SURFACE-TEXTUREDENCAPSULATIONS FOR USE WITH LIGHT EMITTING DIODES.

BACKGROUND

1. Field

The present application relates generally to light emitting diodes, andmore particularly, to surface-textured encapsulations for use with lightemitting diodes that provide for enhanced light output.

2. Background

Light emitting diodes (LEDs) for use as indicators are well known. LEDshave been used extensively for this purpose in consumer electronics. Forexample, red LEDs are commonly used to indicate that power has beenapplied to devices such as radios, televisions, video recorder (VCRs)and the like.

Recently, high-power LEDs have seen increased use in general lightingapplications. For example, power LEDs can now be found in overheadlighting, table lamps, and in automotive application, such as inautomobile headlamps. Typically, high-power LEDs are provided as part ofan assembly comprising a LED mounted to a substrate and protected byencapsulation. Light emitted from the LED passes through theencapsulation before it is visible to a user. However, there is lightloss in the encapsulation layer in the LEDs. This is due in part tointernal reflections occurring at the interface between theencapsulation and the air.

Various techniques have been tried to improve the light output of theLEDs. For example, the addition of a lens to the encapsulation layer hasbeen used to extract additional light. However, the additional lensmaterial impacts the thermal properties of the LED assembly by reducingheat dissipation. Also, the addition of the lens increases the cost ofprocessing and manufacture of the LED assembly.

Therefore, what is needed is a way to increase the optical output ofhigh power LEDs while providing excellent heat dissipation and reducedprocessing and manufacturing costs.

SUMMARY

In one or more aspects, a surface-textured encapsulation layer isprovided for use with one or more light emitting diodes so as to provideincreased optical output, excellent heat dissipation, and reducedprocessing costs.

In an aspect, a light emitting diode apparatus is provided thatcomprises a light emitting diode, and an encapsulation formed upon thelight emitting diode and having a surface texture configured to extractlight.

In an aspect, a method is provided for forming a light emitting diodeapparatus. The method comprises encapsulating a light emitting diodewith an encapsulation having a surface texture configured to extractlight.

In an aspect, a light emitting diode lamp is provided that comprises apackage, at least one light emitting diode disposed within the package,and an encapsulation formed upon the at least one light emitting diodehaving a surface texture configured to extract light.

In an aspect, an illumination device is provided that comprises a powersource, and a light emitting diode lamp in electrical communication withthe power source. The lamp comprises a package, at least one lightemitting diode, and an encapsulation formed upon the at least one lightemitting diode having a surface texture configured to extract light.

In an aspect, a method is provided for forming a light emitting diodeapparatus. The method comprises determining one or more regions of anencapsulation, the encapsulation formed upon a light emitting diode, andsurface-texturing each region of the encapsulation with one or moregeometric features that are configured to extract light.

Other aspects will become apparent after review of the hereinafter setforth Brief Description of the Drawings, Description, and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects described herein will become more readily apparentby reference to the following Description when taken in conjunction withthe accompanying drawings wherein:

FIG. 1 shows a LED assembly with a conventional encapsulation;

FIG. 2 shows a LED assembly with a surface-textured encapsulationconfigured for light extraction;

FIG. 3 shows aspects of a multi-LED assembly with surface-texturedencapsulation;

FIG. 4 shows aspects of three LED assemblies having encapsulationscomprising different surface texturing;

FIG. 5 shows a LED assembly that comprises aspects of surface texturedencapsulation wherein the overall shape of the encapsulation is selectedto provide for additional light extraction;

FIG. 6 shows a LED assembly comprising aspects of an encapsulationhaving multiple surface-textured regions;

FIG. 7 shows an exemplary method for generation surface-texturedencapsulations for extracting light from LEDs; and

FIG. 8 shows exemplary devices having LED's with surface texturedencapsulations as described herein

DESCRIPTION

In various aspects, a surface-textured encapsulation is provided for usewith one or more light emitting diodes so as to provide increasedoptical output, improved heat dissipation, and reduced processing costs.

The following definitions define terms for use in this document.

-   1. Active region—the region in a light-emitting diode where injected    electrons and holes recombine to generate photons in a LED when    current is applied.-   2. “Formed upon” means “deposited, etched, attached, or otherwise    prepared or fabricated upon” when referring to the forming the    various layers.-   3. Package—the assembly of elements that houses one or more LED    chips, and provides an interface between the LED chip(s) and a power    source to the LED chip(s).-   4. Transparent—no significant obstruction or absorption of    electromagnetic radiation in a particular wavelength (or    wavelengths) of interest.

FIG. 1 shows a LED assembly 100 with a conventional encapsulation. TheLED assembly 100 comprises a LED 102 mounted to a substrate 104. Thesubstrate provides electrical power to the LED which converts theelectrical power to light and the light is emitted from the surface ofthe LED 102. The LED 102 is encapsulated with an encapsulation 106 thathas a flat smooth surface as illustrated at 108. During operation, lightemitted from the LED 102 travels through the encapsulation 106 and isemitted from the LED assembly 100 as illustrated at 110. However,because of the smooth flat surface 108 of the encapsulation 106, somelight emitted from the LED 102 is incident upon the surface 108 at anangle that is less than a critical angle. The critical angle is an angleformed between a boundary and incident light and is determined by therefractive index property of the materials at the interface. Lightstriking the boundary at less than the critical angle will be reflectedback into the encapsulation instead of passing through the boundary. Asillustrated at 112, light reflected within the encapsulation 106 is notemitted from the LED assembly 100. Thus, the LED assembly 100 operatesinefficiently and therefore provides reduced light output. ConventionalLED assembles may include additional lens material added to theencapsulation to remove the total internal reflection and to extractmore light. However, the added lens material reduces the heatdissipation properties of the LED assembly 100 and adds additionalprocessing and manufacturing costs.

FIG. 2 shows aspects of a LED assembly 200 with a surface-texturedencapsulation configured for light extraction. For example, the LEDassembly 200 includes an encapsulation 204 that comprises a texturedsurface 206 that is formed upon LED 202. In an aspect, the texturedsurface 206 comprises a field of geometric features or shapes (in thiscase hemisphere shapes) that are stamped, or molded, or patterntransferred, or otherwise formed upon to the encapsulation 204. However,as described below in various aspects, the textured surface 206 maycomprise a variety of geometric shapes.

The textured surface 206 is configured so that light emitted from theLED 202 will incident upon a large portion of the encapsulation surfaceat angles that are greater than the critical angle. This means that lesslight will be reflected and more light will be extracted from the LEDassembly 200 than from the LED assembly 100. And, since the use ofadditional lens material is not needed, the LED assembly 200 providesincreased light output and excellent heat dissipation properties whileavoiding additional processing and manufacturing costs.

In various aspects, the surface-textured encapsulation 204 is suitablefor use with virtually any color LED. For example, the surface-texturedencapsulation 204 will extract additional light emitted from red, blue,green, amber or white LEDs. It should also be noted that thesurface-textured encapsulation can be used with other types of lightsources and is not limited to be used only with LED light sources.Furthermore, the surface-textured encapsulation 204 may be composed ofany suitable material, such as silicone or phosphor.

FIG. 3 shows aspects of a multi-LED assembly 300 with surface-texturedencapsulation. The assembly 300 comprises LEDs 302-308 mounted to asubstrate 310. The assembly 300 also comprises encapsulation 312 have atextured surface 314. The textured surface 314 is configured to extractlight emitted by the LEDs 320-308. Thus, FIG. 3 illustrates that aspectsof an encapsulation with surface-texturing is scalable for use with anynumber of LEDs and these LEDs can be any combination of LEDs ofdifferent colors to increase light output while providing excellent heatdissipation and avoiding the processing costs of additional lensmaterial.

FIG. 4 shows aspects of three LED assemblies 400 having encapsulationscomprising different surface texturing. FIG. 4 illustrates that surfacetexturing comprising a variety of geometric features or shapes may beuse to improve light extraction from LED assemblies.

A first LED assembly 402 is shown having an encapsulation 404 withsurface texturing 406 comprising geometric shapes forming hemispheres.The dimensions of the hemispheres (i.e., radius) are selected to providean increase amount of extracted light as opposed to an untexturedencapsulation. For example, if a square LED is used that has a sidedimension of two millimeters; the radius of the hemispheres may be inthe range of one micrometer to one millimeter. Thus, the radius of thehemispheres is less than the dimension of the LED or other suitablelight source.

It should also be noted that in various aspects, the geometric featuresor shapes may have varying dimensions. For example, the hemispheresshown at 406 may have varying dimensions and are not limited to havingthe same dimensions.

A second LED assembly 408 is shown having an encapsulation 410 withsurface texturing 412 comprising geometric shapes forming cones orpyramids. The dimensions of the cones or pyramids (i.e., base area andheight) are selected to provide a desired amount of extracted light.

A third LED assembly 414 is shown having an encapsulation 416 withsurface texturing 418 comprising random geometric shapes. The randomgeometric shapes may have any dimensions to provide a desired amount ofextracted light. For example, random pyramid shapes having a range ofbase areas and heights may be selected to provide a desired amount oflight extraction.

Thus, the LED assemblies 400 illustrate that surface texturingcomprising a variety of features or geometric shapes may be use toimprove light extraction in accordance with the various aspects.

FIG. 5 shows a LED assembly 500 that comprises aspects of surfacetextured encapsulation wherein the overall shape of the encapsulation isselected to provide for additional light extraction. For example, theLED assembly 500 comprises a LED 502, substrate 504, and encapsulation506. The encapsulation 506 comprises surface texturing 508 in accordancewith the various aspects presented herein. The encapsulation 506 alsohas an overall shape to provide additional light extraction. Forexample, the encapsulation 506 has an overall dome shape (i.e., higherat the center than at the edges) that is configured to provideadditional light extraction. It should be noted that aspects of thesurfaced textured encapsulation are not limited to encapsulations with adome shape as illustrated in FIG. 3 and that any desired overallencapsulation shape may be utilized to provide for increased lightextraction.

Thus, aspects of surface textured encapsulations described herein maycomprise any desired overall shape to improve light extraction.

FIG. 6 shows a LED assembly 600 comprising aspects of an encapsulationhaving multiple surface-textured regions. For example, to illustrate themultiple surface-textured regions, the LED assembly 600 is shown in aside view perspective 604 and a corresponding top view perspective 602.The LED assembly 600 comprises LED 614, substrate 606 and a multiplesurface-textured encapsulation regions.

The multiple surface-textured encapsulation regions comprise a firstregion 608 having a random surface texturing. A second region 610 isprovided that has a hemisphere shaped surface texturing, and a thirdregion 612 is provided that has a cone shaped surface texturing.

Thus, in various aspects, a surface-textured encapsulation may comprisemultiple regions where each region provides surface-texturing usingdifferent geometric shapes. As a result, an increased amount of light isextracted from a LED assembly over that of LED assemblies having smoothand/or flat encapsulations.

Formation of Surface-Texturing

In various aspects, encapsulations having surface-texturing can beformed using a variety of techniques. For example, referring again toFIG. 6, the surface-textured features provided at 608, 610, and 612 canbe formed upon, created by, and/or applied to the encapsulation usingone or more of the following techniques.

-   1. Molding—The encapsulation is molded to include the desired    surface-textured features.-   2. Stamping—The encapsulation is stamped to include the desired    surface-textured features. For example, a partially-cured silicone    encapsulation is stamped with a specially created stamp to form the    desired features on the silicone surface. The silicone is allowed to    fully cure thereby retaining the desired surface-texturing.-   3. Pattern Transfer—A pattern layer is placed on top of the silicone    or phosphor layer encapsulation. The pattern layer is stamped or    molded and then etched so that the stamped or molded pattern is    transferred (or applied) to the silicone or phosphor layer    encapsulation.

FIG. 7 shows an exemplary method 700 for generating surface-texturedencapsulations for extracting light from LEDs. For clarity, the method700 is described below with reference to the surface-texturedencapsulations shown in FIGS. 5-6.

At block 702, an encapsulation material is determined. For example, theencapsulation material may be selected to be silicone or a phosphorlayer.

At block 704, an encapsulation overall surface shape is determined. Forexample, the overall encapsulation surface shape may be approximatelyflat, domed as illustrated in FIG. 5, or any other desired surfaceshape.

At block 706, an encapsulation surface area is determined. For example,once the encapsulation surface shape is determined, the overall surfacearea is determined.

At block 708, encapsulation surface regions are determined. In anaspect, the surface regions divide the surface area determined at block706. The encapsulation may be configured to comprise any number ofsurface regions.

At block 710, surface texturing for each surface region is determined.For example, each surface region may be surface-textured with adifferent geometric shape or feature. Thus, as illustrated in FIG. 6,each region may be surface-textured to provide a desired amount of lightextraction.

At block 712, the encapsulation undergoes a stamping, or molding orpattern transferring process to have the surface shape, surface regions,and surface texturing in each region as configured in the operationsabove. It should also be noted that although several techniques havebeen disclosed herein for forming encapsulations with surface-texturing,virtually any technique or process may be used to generatedencapsulations having surface-texturing as described herein.

Therefore, the method 700 operates to generate surface-texturedencapsulations so that an improved amount of light can be extracted froma LED assembly as opposed to an untextured encapsulation. It should benoted that the method 700 is just one implementation and that theoperations of the method 700 may be rearranged or otherwise modifiedwithin the scope of the various aspects. Thus, other implementations arepossible with the scope of the various aspects described herein.

FIG. 8 shows exemplary devices 800 suitable for use with LED's havingsurface textured encapsulations as described herein. For example, FIG. 8shows a computer 802, a lamp 806 and an illumination device 808. Each ofthe devices shown in FIG. 8 comprises a LED having a surface-texturedencapsulation configured for light extraction as described herein. Forexample, the computer 802 comprises LED 810 and the portable telephone804 comprises LED 812. The LEDs 810 and 812 have surface texturedencapsulations as described herein to provide for increase light outputwith excellent heat dissipation and low processing costs.

The lamp 806 comprises a package 814 and LED 816. The LED 816 has asurface-textured encapsulation configured for light extraction asdescribed herein. The lamp 806 may be used for any type of generalillumination. For example, the lamp 806 may be used in an automobileheadlamp, street light, overhead light, or in any other generalillumination application. The illumination device 808 comprises a powersource 818 that is electrically coupled to a lamp 820. In an aspect, thepower source 818 may be batteries or any other suitable type of powersource, such as a solar cell. The lamp 820 comprises a LED 822 which hasa surface-textured encapsulation configured for light extraction asdescribed herein.

It should be noted that surface textured encapsulations as describedherein are suitable for use with virtually any type of LED, which inturn may be used in any type of illumination device and are not limitedonly to the devices shown in FIG. 8. Thus, the surfaced-texturedencapsulations described herein provide for increased extraction oflight emitted from LEDs and can be used in a variety of deviceapplications.

The description of the disclosed aspects is provided to enable anyperson skilled in the art to make or use the present invention. Variousmodifications to these aspects may be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects, without departing from the spirit or scope of theinvention. Thus, the present invention is not intended to be limited tothe aspects shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein. Theword “exemplary” is used exclusively herein to mean “serving as anexample, instance, or illustration.” Any aspect described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other aspects.

Accordingly, while aspects of surface-textured encapsulations have beenillustrated and described herein, it will be appreciated that variouschanges can be made to the aspects without departing from their spiritor essential characteristics. Therefore, the disclosures anddescriptions herein are intended to be illustrative, but not limiting,of the scope of the invention, which is set forth in the followingclaims.

1. A light emitting diode apparatus comprising: a light emitting diode;an encapsulation formed upon the light emitting diode, the encapsulationhaving a non-flat surface; surface texturing formed upon the non-flatsurface, wherein said surface-texturing comprises one or more regions,wherein each region comprises one or more geometric shapes, and whereinat least one region has geometric shapes of hemispheres; and wherein thenon-flat surface and the surface texturing are configured to enhancelight extraction from the light emitting diode apparatus.
 2. Theapparatus of claim 1, wherein said encapsulation comprises clearsilicone.
 3. The apparatus of claim 1, wherein said encapsulationcomprises a phosphor-containing silicone layer.
 4. The apparatus ofclaim 1, wherein said encapsulation is stamped with thesurface-texturing.
 5. The apparatus of claim 1, wherein saidencapsulation is molded to form the surface-texturing.
 6. The apparatusof claim 1, wherein said encapsulation receives the surface-texturingthrough a pattern transfer process.
 7. The apparatus of claim 1, whereinthe encapsulation has other surface-texturing comprises regions, whereineach region comprises one or more geometric shapes, and wherein the oneor more geometric shapes associated with each of the other regions areselected from a set comprising hemispheres, cones, pyramids, and randomshapes.
 8. The apparatus of claim 1, wherein said encapsulation has anoverall shape that is domed wherein a center portion is higher than sideportions.
 9. The apparatus of claim 1, further comprising multiple lightemitting diodes within the encapsulation.
 10. A method for forming alight emitting diode apparatus comprising: forming an encapsulation upona light emitting diode, the encapsulation having a non-flat surface, thenon-flat surface having a surface texture and an overall shape that areconfigured to enhance light extraction, wherein said forming comprisessurface-texturing one or more regions, wherein each region comprises oneor more geometric shapes, and wherein at least one region has geometricshapes of hemispheres; and wherein the surface texture comprises one ormore geometric shapes dimensioned to be smaller than the light emittingdiode.
 11. The method of claim 10, wherein said forming comprisesforming the encapsulation from clear silicone.
 12. The method of claim10, wherein said forming comprises forming the encapsulation from aphosphor-containing silicone layer.
 13. The method of claim 10, whereinsaid forming comprises stamping the encapsulation with thesurface-texture.
 14. The method of claim 10, wherein said formingcomprises molding the encapsulation with the surface-texture.
 15. Themethod of claim 10, wherein said forming comprises transferring thesurface-texture to the encapsulation with a pattern transfer process.16. The method of claim 10, wherein said forming comprises forming theencapsulation to comprise one or more regions, wherein each regioncomprises one or more geometric shapes, and wherein the one or moregeometric shapes associated with each of the other regions are selectedfrom a set comprising hemispheres, cones, pyramids, and random shapes.17. The method of claim 10, wherein said forming comprises forming theencapsulation to have an overall shape that is domed.
 18. The apparatusof claim 1, wherein the surface texturing comprises a geometric shapeand the geometric shape and an overall shape of the encapsulation aresubstantially the same.
 19. The apparatus of claim 18, wherein thegeometric shape of the surface-texturing and the overall shape iscurved.
 20. The apparatus of claim 18, wherein the geometric shape ofthe overall shape of the encapsulation is domed.
 21. The method of claim10, wherein the one or more geometric shapes of the surface-texturingcomprise one geometric shape and the geometric shape of thesurface-texturing and the overall shape of the encapsulation aresubstantially the same.
 22. The method of claim 10, wherein thegeometric shape of the overall shape of the encapsulation is curved. 23.The method of claim 10, wherein the geometric shape of the overall shapeof the encapsulation is domed.